With
all the ranting and raving over Ford’s BA XR6T and quad-cam V8 engines, the
run-of-the-mill 4.0 litre DOHC straight six is being completely overlooked. But
after a drive of a BA Falcon 4.0 equipped with Jim Mock Motorsport’s DEV3 kit, we
can assure you there is some go-fast
potential!

With
double overhead camshafts, infinitely variable cam timing, 24 valves and the
latest engine management system, the BA 4.0 six offers substantial power from
the factory. Peak power is an impressive 182kW at 5000 rpm.

After
Ford’s mammoth engineering effort with this engine, it should come as no surprise
that there’s limited scope for the aftermarket to achieve peak power – at least,
not without adding forced induction or nitrous... However, it is achievable to
increase the average power output and
to sharpen throttle response.

And
that’s exactly what we found behind the wheel of the Jim Mock Motorsport BA
Falcon XT.

The
throttle response of the JMM BA Falcon (with its manual gearbox) is wonderfully
crisp. In fact, we can’t think of another car we’ve driven that offers better
response – except, perhaps, the Mitsubishi Magna VR-X with manual trans (believe it or
not, the Magna has stunning throttle response). The JMM Falcon’s crisp throttle response is immediately followed by a
mountain of torque, which is greatest between 2000 and 4000 rpm. Performance
falls away toward 6000 rpm - a result of the standard camshafts.

Despite
weighing 1700kg+ and with two people onboard, we hand-timed the JMM BA to 100
km/h in the mid-to-high 6s. That’s decidedly quick and, unlike other modified
performance cars, we found it very easy to get off the line. Just don’t be too
eager when you pop the clutch...

According
to JMM, a stock BA Falcon makes about 140kW at the wheels on their Dyno Dynamics
chassis dyno. Autos are generally a couple of kilowatts below the 140 mark and
manual versions are a couple of kilowatts above. Once brought up to DEV3 spec,
output jumps to a claimed 180kW at the wheels – just 8kW behind what they’ve
seen from a stock XR6 Turbo under the same conditions.

The
subtleties to the upgrade are also impressive.

The
engine fires into life with just a tiny amount longer cranking on the starter motor and
the high-flow exhaust is completely resonance-free and quiet at cruise. Give it
a bootfull and the exhaust howls, but it’s not offensively loud. The engine is
also happy to trundle along in carparks in second gear with absolutely no
surging, stalling or general misbehavior. Jim Mock suggests filling the tank
with premium unleaded for maximum performance and, as we noticed, there’s no
sign of detonation.

Okay,
so that’s the result of modification - what exactly are the
modifications?

The
Jim Mock Motorsport DEV3 BA upgrade builds on the modifications involved in the
DEV1 and DEV2 kits.

DEV1
begins with a 2 ½ inch cat-back mandrel exhaust with two large-body mufflers.
The precise details of the system are a secret as DMM has invested a lot of
R&D in achieving a broad torque curve without resonance or excess noise.
Note that the exhaust for BA Falcon utes is slightly different to those for
sedans and wagons.

DEV1
also includes a high-flow air intake, which comprises a Tickford
over-the-radiator snorkel and a pod filter hidden inside the standard airbox. A
custom plastic adaptor is required to secure the filter to the airbox. JMM
defends their choice of installing a pod filter inside the factory airbox by citing
their dyno development figures.

Another
interesting component of the DEV1 kit is performance spark plugs sourced from
America.
Again, these are dyno tested.

The
entry-level DEV1 upgrade for BA 4.0 Falcons retails for just AUD$695 (AUD$50
more for utes). JMM have seen this kit reach 148kW at the wheels – about 8kW
more than stock.

DEV2
– the mid-level kit – employs everything found in DEV1 and adds JMM’s latest
“Scavenger” headers along with a high-flow cat converter and adjoining 2 ½ inch
pipe. The headers are the result of extensive dyno testing and JMM tells us
their design ended up being about halfway between their scavenger and race
series headers used in SOHC 4.0s. We’re told that the Ford six is extremely
sensitive to combustion chamber scavenging. Note that the headers are also HPC’d
to keep heat away from the nearby engine bay wiring.

DEV2
adds a significant AUD$885 to the price of the DEV1 kit, bringing the total to
AUD$1580 (AUD$1630 for utes). However, the power gain justifies the extra cost –
JMM claim about 168kW ATW. That’s a full 20kW more than DEV1 and 28kW more than
stock.

Note
that a slightly different version of this kit is also available – the DEV2A
upgrade. DEV2A incorporates a 3 inch mandrel exhaust and cat converter (an early prototype is shown here), instead
of the 2 ½ inch arrangement used in the usual DEV2 kit. The bigger exhaust adds
AUD$260 and provides an extra 4kW, for a total of 172kW at the
wheels.

In
addition to providing improved drivability thanks to the UniChip, the DEV 3
upgrade ups the ante to 180kW at the wheels (see graph). The UniChip module
contributes AUD$990 for an all-up cost of AUD$2570 (50 bucks extra for utes).

And
the 3 inch exhaust upgrade? Well, at the time of writing, JMM were yet to see
any extra power over their 2 ½ inch system. At around 180kW at the wheels, we’re
told the DOHC Ford six is crying out for a new set of camshafts. JMM is
currently working on this.

For
now, though, the DEV 3 kit is a very well behaved and cost-effective upgrade for
anyone with a naturally aspirated BA six. Fear not – you are guaranteed to feel
the difference over a stocker!